Primary: To determine whether additional boosting with soluble recombinant gp160 vaccine (VaxSyn) after priming with a vaccinia-HIV envelope recombinant (HIVAC-1e) provides a significant advantage in the degree and duration of immunogenicity. Secondary: To learn more about the safety of the combination use of the two HIV envelope vaccines in the study (VaxSyn and HIVAC-1e).

Recent Phase I trials conducted at the AIDS Vaccine Units have shown that antibodies have persisted in most recipients for 6 months after boosting, and responses seem significantly higher and more persistent than responses achieved by just two doses of soluble protein vaccine alone or two doses of HIVAC-1e alone. This study tests in a previously recruited cohort of volunteers whether additional boosting with soluble recombinant gp160 results in increased immunogenicity of longer duration.

Recent Phase I trials conducted at the AIDS Vaccine Units have shown that antibodies have persisted in most recipients for 6 months after boosting, and responses seem significantly higher and more persistent than responses achieved by just two doses of soluble protein vaccine alone or two doses of HIVAC-1e alone. This study tests in a previously recruited cohort of volunteers whether additional boosting with soluble recombinant gp160 results in increased immunogenicity of longer duration.

Twelve volunteers who have previously received two doses of HIVAC-1e (or DryVax) and two doses of gp160 receive an additional boost of gp160 at 12-20 months after the last boost and an additional dose of HIVAC-1e at least 9 months after the final gp160 boost.

Inclusion Criteria

Patients must have:

• Normal history and physical exam.
• Negative ELISA for HIV.
• Negative HIV p24 antigen test.
• Normal urinalysis.

Prior Medication: Required:

• Two prior doses of HIVAC-1e (or DryVax) and two prior doses of gp160 vaccine.

Exclusion Criteria

Co-existing Condition:

Patients with the following symptoms and conditions are excluded:

• Risk factors for HIV infection including active intravenous drug use and more than 2 sexual partners.
• History of immunodeficiency or chronic illness.
• Hypersensitivity to insects.
• Medical or psychiatric condition that makes it unlikely the patient will comply with the protocol.

Patients with the following prior conditions are excluded:

• History of immunodeficiency or chronic illness.

Prior Medication:

Excluded:

• Immunosuppressive medications.

Prior Treatment:

Excluded:

• Blood or blood product transfusion within the past 6 months.

Risk Behavior: Excluded:

• Intravenous drug use.
• More than 2 sexual partners.